Conventional scanners and imagesetters commonly employ external or internal drums for media positioning. External drum scanners such as the Scitex ELP external drum scanner, utilize rotary motors of various types for media positioning. The cost of such motors becomes extremely high when highly accurate positioning and repeatability is required.
Internal drum imagesetters, such as for example, the Scitex Dolev 200, utilize pairs of rollers for drawing film out of a film cassette and precise positioning thereof inside a drum.
Precise positioning becomes increasingly difficult as the size of the film to be positioned increases. Roller based positioning systems encounter difficulties in providing consistently precise positioning.